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- #| -*-Scheme-*-
- Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
- 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
- 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Massachusetts
- Institute of Technology
- This file is part of MIT/GNU Scheme.
- MIT/GNU Scheme is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or (at
- your option) any later version.
- MIT/GNU Scheme is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with MIT/GNU Scheme; if not, write to the Free Software
- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
- USA.
- |#
- ;;;; Unit systems
- (define unit-environment generic-environment)
- (define (express-as num target-unit-expression)
- (let ((target-unit-expression-value
- (eval target-unit-expression unit-environment)))
- (cond ((with-units? target-unit-expression-value)
- (let ((target-val (u:value target-unit-expression-value))
- (target-units (u:units target-unit-expression-value)))
- (express-in-given-units (g:/ num target-val)
- target-units
- target-unit-expression)))
- ((units? target-unit-expression-value)
- (express-in-given-units num
- target-unit-expression-value
- target-unit-expression))
- (else num))))
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